1. Technical Field
This invention relates to audible alert devices and more particularly to an audible alert device including pulse width modulated signal generation, resonant frequency determination and decibel peaking and a process for the manufacture and programming of a programmable and/or self adjusting audible alert device.
2. Background
Currently, the manufacture of an audible alert device, for instance a backup or reverse motion alert device, includes the steps of circuit assembly and connection of the circuit to a transducer, commonly a voice coil, enunciator or speaker and the circuit is installed in a housing. Next, the circuit may be adjusted, tuned or programmed, for specific or desired output characteristics defining an operation mode. Following assembly of the circuit, transducer and housing, an internal cavity of the housing in which the circuit is installed is cast with a fluid sealing material, for instance, a molten epoxy based potting mixture which cures and hardens to seal the circuit from environmental elements.
Following completion of assembly, as previously described, performance of the circuit may be tested to assure that the circuit and transducer are performing according to selected criteria. Performance criteria may specify output level, output frequency or tone or pulse pattern characteristics all of which may define an operation mode. Devices, for which manufacturing is complete, may be rejected as a result of a failure to meet such criteria. It is believed without being bound by such theory, that the step of potting the circuit within the housing may, in some instances, result in a change in circuit output or performance resulting in a failure of the alert device to meet specific performance criteria and therefore, rejection of the alarm.
There may be advantage in providing a method for the manufacture of an audible alert device which permits adjustment or programming of the circuit following casting with a fluid sealing material, for instance, molten epoxy. Similarly, it is believed that there may be advantage in providing an audible alert device including a circuit which may be programmed or adjusted following casting of the circuit with a fluid sealing material.
Also according to current practices, a separate circuit may be required for each production model, depending on desired output characteristics, i.e. operating output frequencies, output level and signal pattern, and therefore multiple assembly lines, resources or facilities may be required for each of several production models. It is also believed, therefore, that there may be advantage in providing a method for the manufacture of an audible alert device which permits programming of a single circuit to exhibit a pre-selected operation mode selected from a group of operation modes. Each operation mode includes pre-selected output levels, output frequencies or tone or pulse patterns. Similarly, it is believed that there may be advantage in providing an audible alert device including a circuit which may be programmed to exhibit one or more pre-selectable operation modes. One of the obstacles to programming or adjusting the audible alert device circuit following potting with a sealing substance has been the fact that the circuit is largely inaccessible for such programming or adjustment.
There may be advantage therefore in providing a method for the manufacture of an audible alert device which permits adjustment or programming of the circuit, following casting with a fluid sealing material, by transmitting data over one or more conductors that connect to the circuit and, are accessible following casting with a fluid sealing material. Similarly, it is believed that there may be advantage in providing an audible alert device including a circuit which may be programmed or adjusted following casting of the circuit with a fluid sealing material, by transmitting data over one or more power conductors that connect to the circuit and are accessible following casting with a fluid sealing material.
Driving a transducer in an audible alert device, for instance a voice coil, enunciator or speaker at a resonant frequency is considered most efficient and therefore desirable. Following manufacture or as a result of manufacturing process or routine operations, an audible alert device may be subjected to any of a wide variety of environmental and operational conditions. For instance, variations in temperature and humidity, variations in air quality and age of the device may all affect output characteristics of the audible alert device.
There may be advantage found in providing an audible alert device which includes a self adjustment feature which operates by generating a digital feedback signal representative of the current used by the transducer, measured for instance by a sense resistor, which enables adjustment of the circuit so that the circuit operates at an actual resonant frequency as opposed to a calculated resonant frequency.
Similarly, it is believed that there may be advantage in providing a method for manufacturing an audible alert device including an adjustable or self adjusting feature which operates by generating a digital feedback signal representative of the current used by the transducer which enables adjustment of the audible alert circuit so that the circuit operates at an actual resonant frequency as opposed to a calculated resonant frequency.
Various objectives of the present invention may therefore include:                a) providing a method for pulse width modulated signal generation in an audible alert device and an audible alert device including a pulse width modulated signal generation capability;        b) providing a method for resonant frequency determination in an audible alert device and an audible alert device including a resonant frequency determination capability;        c) providing a method for decibel peaking in an audible alert device and an audible alert device including decibel peaking capability;        d) providing a self adjusting audible alert device and a process for the manufacture and programming of a self adjusting audible alert device;        e) providing a method for programming an audible alert device circuit to exhibit a pre-selected operation mode selected from a group of operation modes, each operation mode having pre-selected output levels, output frequencies or tone or pulse patterns;        f) providing an audible alert device and a process for the manufacture and programming of an audible alert device including a self adjustment feature which operates by generating a digital feedback signal representative of the current used by the transducer, and which enables adjustment of the circuit so that the circuit operates at an actual resonant frequency determined either at the time of manufacture, upon startup of the alarm or continuously during operation;        g) providing a method for the manufacture of an audible alert device and an audible alert device including a circuit which may be programmed or adjusted following casting of the circuit with a fluid sealing material; or        h) providing a method for the manufacture of an audible alert device and an audible alert device including a circuit which may be programmed or adjusted following casting of the circuit with a fluid sealing material, by transmitting data over one or more power conductors that connect to the circuit and are accessible following casting with a fluid sealing material.        